1. Field of the Invention
This invention relates generally to communications networks. More particularly, it relates to a control scheme to improve the control of Quality-of-Service (QoS) parameters in a packet or circuit network, e.g., in a voice-over-IP network.
2. Background of Related Art
Quality-of-Service (QoS) is one of the most important factors in communications and switching equipment. An important measure of QoS, especially in switching systems, with real-time applications support, is the processing delay that signaling messages encounter. Average processing delays are an important measure, particularly in multimedia applications, as the switching equipment is required to handle a significant amount of real-time traffic, e.g., voice and/or video.
Real-time signals are delay-sensitive in that they suffer performance and QoS degradation in the case of excessive and/or uncontrolled switching delays at any particular time in the communications network. While a predictable and consistent time delay through a network can be accommodated and associated with a particular level of QoS, a variable and inconsistent time delay becomes difficult and inefficient from a network standpoint because the QoS will likely be rated at the level of the worst case delay in the variable delay environment. Conventional networks tend to suffer from an inconsistent service delay due to conventional admittance techniques such as packet queuing.
There is a need for a more efficient technique and apparatus to improve the inconsistency and variability in service delays in a switching network.
In accordance with the principles of the present invention, an admission technique comprises defining a length of a control interval. A delay of queries or messages processed by a network system during a first control interval is measured. A number of queries admitted to the system during a second control interval after the first control interval is maintained based on the measured delay to target a desired delay for the communications system.
A query admission control loop comprises a query delay measurement module to measure the delay through the switching network system during a first control interval. An error calculation module determines a delay difference between the measured queries delay and a target delay. A controller adjusts a number of queries allowed into the queries network system during a second control interval from a number of queries allowed into the packet network during the first control interval based on the determined delay difference.